Quote from FCC filing: "This STA is necessary to authorize Starship suborbital test vehicle communications for SpaceX Mission 1569 from the Boca Chica launch pad, and the experimental recovery following the suborbital launch. Recovery is limited to 2 functions: (1) prelaunch checkout test of the TC uplink from the ground station at Boca Chica (less than five minutes in duration) and (2) experimental uplink testing from the ground station at Boca Chica during descent. Trajectory data will be provided directly to NTIA, USAF, and NASA. All downrange Earth stations are receive-only. Launch licensing authority is FAA Office of Commercial Space Transportation."

They have 4 boosters ready right now (B1046, B1048, B1049 and B1051, B1056 is for CRS-19 in December). Enough for 4 launches. They also learned how to refurbish the launch pads pretty fast. Between CRS-18 launch and Amos-17 vertical on pad for a static fire were only 7 days. What I want to say is that they improved their capabilities on a high frequent launch scheduele pretty much in the last months.

You're right, boosters will likely not be the problem. But for IFA Crew Dragon needs to be ready, and for Anasis and JCSat, the payload or payload integration can very easily get some minor delays. Just saying: don't hold your breath.

It is worth noting that the important date here is when it begins and not when it ends because that is not chosen by SpaceX. They fill the permit for X date and they're given a standard 6 month period to conduct the experimental activity for which they are requesting it.

Do we really think that they're running the same race? Bezos doesn't seem to be concerned about anything beyond cislunar space and Elon is unabashedly aiming for Mars. There's plenty of room in the market for both.

The only reason I can think of would be to validate the structure if it deviates substantially from the hopper or some other known design. Given that, they might be confident enough in their ability to model the structural forces sufficiently to not be too concerned.

I was thinking they would fly the first SH flights with 19 engines, which are enough to get the booster with no second stage to the edge of space, but if they decide the first flight will just be a 150 m takeoff and landing, then 7 should be enough.

It's gonna need quite a few engines, and that means it's probably going to need more than a basic concrete pad to take off as well. We'll have plenty of advance notice when they intend to start flying Super Heavy.

Probably true. It makes sense to do this before trying to fly Super Heavy on a full flight trajectory to 50-100 km altitude and 2 to 2.5 km/sec top speed and then doing the return to launch site (RTLS) maneuvers.